Selection Of The Motor Cable; Motor Cable Length And Conducted Interferences At Ac Supply; Figure 21: Symmetrical Motor Cable; Table 21: Max. Motor Cable Length - KEB COMBIVERT F6 Instructions For Use Manual

cONNecTION OF THe POWer UNIT

4.2.5.7 Selection of the motor cable

The correct cabling as well as the motor cable itself play an important part in case of
low power in connection with long motor line lengths. Low-capacitance cable (phase/
phase<65 pF/m, phase/screen<120 pF/m) at the inverter output have the following ef-
fects:
•
•
PE
U
PE
W
Figure 21: Symmetrical motor cable

4.2.5.3 Motor cable length and conducted interferences at AC supply

The maximum motor line length is depending on the capacity of the motor cable as well
as on the EMC emitted interference. External measures must be taken here (e.g. the
use of a line filter). The following information is valid for the operation under rated con-
ditions and the use of KEB listed filters under chapter =>
Inverter
size Motor cable (standard)
21
22
23
24
Table 21: Max. motor cable length
allow major motor cable lengths (=> motor line length)
better EMC properties (reduction of the common-mode output currents to earth)
The use of shielded motor cables with symmetrical structure is
recommended for higher motor power (from 30 kW). In these
cables the protective earth conductor is tripartite and evenly ar-
ranged between the phase lines. A cable without protective earth
conductor can be used if local regulations so permit. Then the
V
protective earth conductor must be laid externally. Certain cables
also permit the shield for the use as protective earth conductor.
For this, observe the details of the cable manufacturer!
PE
Max. motor cable length shielded
in accordance with
category c2
50 m
The line length can be increased significant by using motor chokes or motor
filters. KEB recommends the use of motor chokes or filters for a line length upto
50 m.
EN 61800-3
Motor cable (low capacitance)
100 m
4.3.1!
max. leakage
current
(at f ≤ 100 Hz)
N
< 5 mA
55